The over-all goal of this two-year project will be to develop and refine a novel three-dimensional tumor model in which we can measure spatial distributions of microenvironmental parameters and directly compare these with alterations in cellular physiology and functional genomics. We propose three Specific Aims to develop and initially validate this new experimental model system. The first Aim is to develop a novel three dimensional cell culture chamber for spatially-resolved cell physiology, gene and protein expression. This chamber will provide steady-state gradients of microenvironmental factors that are spatially correlated with gradients in cellular physiology, metabolism and gene/protein expression. The second Aim is to develop NMR 1-D imaging methods for oxygen, pH, glucose/lactate and cell density/flow. These methods will provide 1-D maps of concentration gradients that are spatially correlated with the corresponding gradients in cellular parameters. The third Aim will be to develop and validate a mass transport model for fitting the NMR concentration profiles in order to obtain cellular metabolic parameters. The aims are highly interactive: improvements in spatial resolution of the NMR imaging methods will be coupled to development of a more tissue-like system for cell culture, and visa versa. The data from each iteration of the system will be analyzed using the mass transport model, which will, in turn, be refined based on the results obtained. This will be the first 3-D cell culture system available for measuring the effects on tumor cells of exposure to known combinations of metabolite and catabolite gradients. Although the aims of this two-year application are primarily to develop, validate and refine the new model system, we produce preliminary data demonstrating the usefulness of this system for our ongoing projects in studying the tumor microenvironment. We anticipate application of this new system to answer fundamental questions about the regulation of cellular metabolism, proliferation, physiology, and gene/protein expression under multi-component microenvironmental stress, which closely mimics the situation in tumors. This system will be useful in a wide variety of other basic and applied cancer research areas, including drug development, radiobiology, and non-invasive diagnosis. The new tumor model system should also serve as an excellent platform for improving biomedical imaging, particularly NMR microimaging. The system is also potentially very useful for applied research on cell culture systems for biomaterial production and artificial organs. Finally, this system should prove useful for investigating the regulation of metabolism and physiology in microbial systems, a current area of intense interest.